The instant invention relates to a flat type feeder cable useful for feeding electrical power or data from a fixed or stationary electrical power or data supply terminal to a moving apparatus such as an elevator. More particularly, this invention relates to a flat type feeder cable for feeding electrical power or data from a stationary terminal to a moving apparatus such as an elevator disposed to travel vertically in a narrow or restricted space, i.e., an elevator well.
A feeder cable connected at one end to a stationary source of electrical energy and its other end connected to a moving apparatus is generally referred to as a traveling/lighting or moving cable. After installation, use of the cable involves repeatedly subjecting the cable to various types of mechanical action resulting in bending and torsion. Because a feeder cable used in connection with an elevator is suspended between a fixed electrical power or data supplying terminal at one of its ends and the other end terminated in the elevator, the intermediate portion of the cable naturally hangs in a bent U shape configuration. This bent portion is caused to shift along this entire length in response to the up and down movement of the elevator car, thus subjecting the cable to repeated bending action over its entire length. Any cable used for this purpose must possess excellent flexibility in order to withstand such repeated bending.
The prior art has recognized the problems associated with feeder cable and has attempted to solve the problem in several ways, one of which is disclosed in U.S. Pat. No. 4,227,041. This disclosure attempts to solve the feeder cable problems by an arrangement using a plurality of even numbered cores, each core being made from a plurality of strands and each strand being made from a plurality of stranded copper conductors surrounded by a jacket. One-half of the cores are so constructed that the strands of the cores have a direction of lay in one direction ("S" stranding for example) and the balance of the strands are made from cores that have a direction of lay opposite from that of the first mentioned strand ("Z" stranding for example). Even though this prior art discloses strength members, such strength members are always disclosed as being embedded in a jacket that surrounds the strands. Applicant has found that most if not all of the load (tensile) stresses one encounters in a feeder cable system employing the feeder cable of U.S. Pat. No. 4,227,041 falls mainly on the electrical conductors, not on any strength members that may be present. This prior art teaching contemplates an even number of stranded members, one-half of which have a direction and degree of lay opposite from that of the other half throughout the entire length of each strand.
Applicants have discovered a S-Z type stranded cable construction that permits all of the tensile stress applied to the cable to be placed solely on strength members and further permits an even or odd number of stranded members.
The foregoing features of the present invention will be apparant to those skilled in the art from the following detailed description taken in connection with accompanying drawings in which: